The present invention relates to electronic devices for detecting atrial fibrillation and in particular to a device providing improved patient mobility and reliable long-term monitoring.
The human heart normally beats anywhere from 60 to 80 beats per minute when a person is at rest. In atrial fibrillation, the atria of the heart may beat 400 to 600 times per minute with the ventricles responding irregularly at a rate of 170 to 200 times per minute.
Diagnosis of atrial fibrillation normally requires that a qualified professional review an electrocardiograph (ECG) in which the electrical impulses from the heart are recorded and displayed in chart form. The electrical impulses are measured by electrodes attached at a number of locations to the patient""s chest.
Episodes of atrial fibrillation, although serious, can be unnoticed by the patient. Yet it is desirable that atrial fibrillation be treated within 48 hours of its onset. One possible solution is the use of a xe2x80x9ccardiac event recorderxe2x80x9d, a portable ECG recording device carried by the patient and communicating with electrodes worn under the patient""s clothing and adhesively attached to the patient""s skin. Such recorders may provide algorithms for monitoring the ECG signal and may report to the users that atrial fibrillation has begun. Recorders of this type may also record a rolling xe2x80x9cwindowxe2x80x9d of ECG data using solid state computer memory. In this latter case, the recorded ECG data may be transmitted over phone lines or the like for review by a qualified physician.
Unfortunately, the cardiac event recorder is not a practical tool for providing a warning of the onset of atrial fibrillation, a condition that can occur unexpectedly at any time in later life. The need for the patient to carry the cardiac event monitor about during the day and the continuous attachment of electrodes is impractical for long term monitoring that may span decades.
The present inventors have recognized that monitoring ECG signals at a regular daily time for a brief period can reliably detect incidences of atrial fibrillation. Such regular monitoring can be provided by a unit which makes only momentary electrical contact with the patient, possibly contact with the patient""s hands. An immediate evaluation of the patient""s ECG signals is made, and if no atrial fibrillation is found, the patient is so informed and may go about his or her business for the remainder of the day, unencumbered by monitoring leads and equipment. The present invention thus opens the possibility of extremely long term monitoring of at risk patients with minimal intrusiveness to the patient""s daily life.
Specifically then, the present invention provides a monitor for atrial fibrillation including a first and second momentary contact electrode sized to contact the patient. An atrial fibrillation detector circuit communicates with the first and second momentary contact electrodes and executes a stored program to receive an ECG signal from a patient touching the first and second momentary contact electrodes and detect a likelihood that the patient is experiencing atrial fibrillation. An output signal is provided to the patient if the likelihood is above a predetermined threshold.
Thus it is one object of the invention to provide a method for monitoring a patient for atrial fibrillation that is far less intrusive than typical cardiac evaluation monitors using chest electrodes and thus which makes long term monitoring possible.
The first and second momentary contact electrodes may be portions of handles graspable by the patient""s right and left hand or may be finger pads or posts sized to contact the patient for an ECG reading.
Thus it is another object of the invention to provide for tabletop or even smaller monitor implementations the latter which may be easily carried with the patient.
The output to the patient may be an illuminating indicator indicating either that atrial fibrillation was found or not.
Thus it is another object of the invention to provide immediate feedback to the patient as to whether there is a likelihood of atrial fibrillation.
The monitor may include a recording media and the atrial fibrillation detector circuit may record the received ECG signals subsequent to the patient touching the first and second momentary contact electrodes. The ECG signals may be the patient""s current ECG signals or those recorded previously during the patient""s use of the device.
Thus it is another object of the invention to provide not only indication to the patient of a likely episode of atrial fibrillation, but also provide a recording of the ECG signals for review by a qualified healthcare professional.
The monitor may include a communication circuit and the atrial fibrillation detector may communicate the ECG signals to the communication circuit for transmission to a remote site.
Thus it is another object of the invention to simplify the process of reviewing the ECG signals by allowing the data to be readily communicated over communication media.
The monitor may include an alarm clock circuit providing a second output signal to the patient to remind the patient to grasp the electrodes. Further, the monitor may include a text display communicating with the atrial fibrillation detector circuit to provide text messages instructing the patient in touching the first and second momentary contact electrodes and remaining in contact with the elements prior to generation of the output signal.
Thus it is another object of the invention to provide features to simplify operation of the device and to encourage the patient in regular use of the device.
The foregoing objects and advantages may not apply to all embodiments of the inventions and are not intended to define the scope of the invention, for which purpose claims are provided. In the following description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by way of illustration, a preferred embodiment of the invention. Such embodiment also does not define the scope of the invention and reference must be made therefore to the claims for this purpose.